Contacts for bond pads for high power integrated circuits commonly have an aluminum interface. Aluminum is used as the last layer of interconnect as well as bond pad metal with gold wire bonded to the aluminum bond pads. For better durability at higher temperature, gold may be used for the bond pad. A gold bond pad is similar to the gold bumps used for tape automated bonding (TAB) that do not require any wire bonds. At higher temperatures, however, such as continuous junction operating temperatures above 125 degrees Celsius, there have been life span limitations with this approach. For applications such as engine control, it is desirable to withstand the higher temperatures for longer life span. At the higher temperatures the gold will eventually diffuse into the aluminum, which causes the area of the aluminum that has the diffused gold to become brittle and weak. When this happens, the diffused region is likely to crack and cause a failure. A number of barrier metals such as titanium tungsten (TiW), titanium tungsten nitride (TiWN), chromium, and platinum have been proposed. All, although generally effective, still have limited barrier lifespan at the higher temperatures.
Thus, there is a need for a contact between an interconnect layer and the overlying bond pad metal that improves durability without adversely impacting cost or unduly adding to process complexity.